Behavioral economics is the application of microeconomic concepts (e.g., consumer demand) and measures within the experimental analysis of behavior. Recent behavioral-economic research suggests that relative reinforcer efficacy is not a singular construct, but should instead be understood as several different components of consumer demand. According to this model, relative reinforcer efficacy may be completely assessed only by measuring a) demand intensity (e.g., drug consumption when drug access is unconstrained), b) elasticity of demand (sensitivity of consumption to price fluctuations), c) P-max (price at which demand shifts from inelastic to elastic) and d) O-max (peak response rate maintained by the reinforcer). Limited empirical evidence supports this analysis and suggests that these measures may be used to predict other measures of reinforcer efficacy (e.g., breakpoint and preference) even when the latter measures disagree (e.g., higher breakpoints maintained by cocaine than methylphenidate but no preference between the drugs in a choice situation). The proposed research will address a limitation of the extant behavioral-economic literature: Only three experiments have thus far examined the relation between the four demand measures noted above and more traditional measures of relative reinforcer efficacy. One of these studies employed only hypothetical rewards and one failed to demonstrate concordance between all measures. Thus, the evidence for the superiority of the behavioral economic account is presently limited. The proposed experiments will assess relative reinforcer efficacy in a closed economy (access to reinforcers is obtained only during the experimental sessions) using steady-state experimental designs. Experiment 1 will examine preference between two reinforcers across a broad range of prices. Demand curves collected over the last two years with these reinforcers will be used to predict a) preferences across the range of prices, b) peak response rates, and c) progressive-ratio breakpoint. Correct predictions will support the behavioral economic account of relative reinforcer efficacy. Experiment 2 will assess the same predictions using drug (alcohol self-administration) and non-drug reinforcers.